code: def longest_period_from_frequency_str(freq_str: str) -> int:
      offset = to_offset(freq_str)
      return (
          FREQ_LONGEST_PERIOD_DICT[norm_freq_str(offset.name)]
          // offset.n
      )
  
imports: from functools import partial
  from typing import List, Optional
  import numpy
  from mxnet.gluon import HybridBlock
  from pandas.tseries.frequencies import to_offset
  from gluonts.core.component import validated
  from gluonts.dataset.common import Dataset
  from gluonts.dataset.field_names import FieldName
  from gluonts.dataset.loader import DataLoader, TrainDataLoader, ValidationDataLoader
  from gluonts.model.predictor import Predictor
  from gluonts.mx.batchify import batchify
  from gluonts.mx.distribution.lds import ParameterBounds
  from gluonts.mx.model.estimator import GluonEstimator
  from gluonts.mx.model.predictor import RepresentableBlockPredictor
  from gluonts.mx.trainer import Trainer
  from gluonts.mx.util import copy_parameters, get_hybrid_forward_input_names
  from gluonts.time_feature import TimeFeature, norm_freq_str, time_features_from_frequency_str
  from gluonts.transform import AddAgeFeature, AddObservedValuesIndicator, AddTimeFeatures, AsNumpyArray, CanonicalInstanceSplitter, Chain, ExpandDimArray, RemoveFields, SelectFields, SetField, TestSplitSampler, Transformation, VstackFeatures
  from .issm import ISSM, CompositeISSM
  from ._network import DeepStatePredictionNetwork, DeepStateTrainingNetwork
label_desc: Use image node_id 1 for calling a global function with example usage: longest_period_from_frequency_str(freq_str) and returns: unknown